When you talk about simulation, the thoughts go to flight simulators and even video games. The simulation has a wide application in different areas, especially in process engineering, which is where the authors of this book focus on. Simulation is, along with statistics, one of the most used techniques for process analysis. It seems that its popularity is increasing, and this is due to the developments in computer technology. The current simulation environments have benefited from better graphics and visuals, as well as lower computation times. In that sense process modeling is developed using Petri nets and simulation with SIMIO, which has proven to be very efficient in the development of industrial-size simulation models.